Download XLi Time & Frequency System

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Have Quick Output with selectable TFOM (87-8016-6)
The Have Quick Out card generates Have Quick time code on four rear-panel BNC connectors.
Use F128 to view the status of the Have Quick Out Option card. See “F128 – Have Quick Output
Configuration” on page 165.
Have Quick Output Specifications
Frame rate:
1 Hz
Accuracy:
1 µS
Stability:
Stability is determined by the XLi’s oscillator specifications
Level:
5V CMOS Logic
Qty:
4
Have Quick Signal Characteristics
2
1
The Have Quick Out signal employs bi-phase (Manchester II) transmission at approximately 1667 bits
per second. A logical one is defined as 300 microseconds of a low state followed by 300 microseconds
of a high state. A transmission of 240 milliseconds of logic ones (400 bits) precedes the start of message
indicator (16 bits) followed by time, day of year, year and TFOM message (96 bits).
The transmission is initiated on a time mark, so that the first bit of the 400 “ones” starts within
1 microsecond of the leading on-time edge of the system 1PPS.
The start of message indicator that follows the “ones” verifies that the time, day of year, year and TFOM
message will follow. Each 8 bit character in the data message (time of day, day of year, year and TFOM)
is defined by a modified 8:4 Hamming Code. The two start-of-message characters, (8 bits each) are not
in the modified Hamming Code.
5
Refer to ICD-GPS-060 Rev A section 4.4.5 for the Have Quick interface requirements.
HaveQuick with selectable TFOM
The Have Quick output option currently meets ICD-GPS-060 Rev A. It will be modified to provide
HaveQuick with Time Figure of Merit (TFOM per the standard) or without TFOM. Selection is via the
Keypad / Display, RS232/422 and the Network port via telnet and HTML.
HaveQuick with TFOM Output:
Signal characteristics
The Have Quick signal employs biphase (Manchester II) transmission at approximately 1667 bits per
second. A logical one is defined as 300 microseconds of a low state followed by 300 microseconds of a
high state. A transmission of 240 milliseconds of logic ones (400 bits) precedes the start of message
indicator (16 bits) followed by time, day of year, year and TFOM message (96 bits).
XLi Time & Frequency System
XLi-man, Issue 8, 6/17/2008, Rev. H
219